This invention relates to improvements in packing machines for packing products in mesh bags with handles. The products to be packed may be fruit, vegetables or other food products of all classes and, in general, any product or object to be packed forming a bag, normally with a total weight or predetermined amount. The invention also relates to improvements in packing machines for packing products in mesh bags formed from tubular mesh forming made of plastic material.
An automatic machine for the shaping and continuous closing of mesh bags obtained from a tubular netting is known, which is disclosed in the Spanish Invention Patent No. 475.372 granted to Mr. Agustin Dauder Guardiola.
The machine disclosed in the aforementioned Spanish patent is basically characterized by the fact that it includes a set of two vertically disposed telescopic tubes with the inside tube fixed and the outside tube mobile. A third removable tube is placed on the set that carries a certain amount of the tubular mesh. In turn, the set of the three tubes is communicated at the top with a hopper for supplying product to be packed, which product had previously been measured in weight and number.
The mobile tube is activated in the downwardly axial direction by an adjustable stroke cylinder, thereby pulling part of the mesh for shaping a bag with suitable capacity for the amount of supplied product. The mesh is first closed at its base or lower end. The mobile tube is immediately returned to its initial position. There are means that strangle and collect the mesh part. The means includes two sets of blades each which act on both sides of the mesh, moving it in a horizontal transversal plane as regards the axis of the mesh on level with the lower end of the mobile tube in its initial position.
The aforementioned sets of blades are overlapped in their active position. The upper set of blades provides a support for the bottom of the bag that received the product discharged by the hopper. The blades of the upper set have a narrow part that, in collaboration with the angular edge of the blades of the opposite set, shape the strangling of the mesh. On the bottom of the narrow part, there is a cutting and stapling lather head, which is integral with the upper blade set and located on the aforementioned vertical axis of the telescopic set.
Operation of the lather head causes the mouth of the already filled bag and the bottom of the next bag to close. Then the blades are separated and a new cycle is started.
The bags obtained from this machine do not have a handle and each bag is filled with its bottom resting on a stiff support resulting from the set constituted by the upper pair of blades, whereby the first portion of the product to be packed hits the stiff support with the mere overlapping of the mesh.
There is another known machine wherein an additional band to print data (type, class, weight and others) of the products contained in the bags and/or to identify their origin must be added. This band is secured only by welding its two ends and the rest is free. That is, bags without handles are obtained from this machine. Furthermore, the structure of the last mentioned known machine gives rise to a limited performance due to the time it takes to prepare it and the welding.
Also known is a conventional machine supplied by a plastic material band, specifically a mesh material, that cuts a piece of the band at a certain length based on the size of the bag to be obtained, folds it horizontally in the middle and joins it by heat welding or sewing of the vertical ends of the two opposite walls. Normally, two joined handles are respectively fastened to each of the two walls of the bag so obtained.
The resulting bag has the disadvantages of increased fabrication costs, and that it cannot be closed in the case of an eventual and more than possible fall of the products contained therein. Furthermore, the bag cannot be completely filled as its mouth is not closed, and this therefore does not guarantee the content of the bag for the buyer.
According to the above, the upper mouth of this last mentioned bag remains open and does not constitute a closed bag with the products inaccessible to the buyer, the access to which requires breaking the upper part of the bag by conventional means (for example, scissors).
On the other hand, the bags open at the top are used by the buyers for filling them with the products purchased in a shopping center. These open bags are bought in specific shops. In contrast, the closed bags are closed packages once filled and sealed, with the particular products to be sold by the shops in question. In other words, the open bags have another application than that of the closed bags, and their marketing channels are different.
The packing machine for packing products in mesh bags with handle are provided with improvements that include, in a linked way, supply means of a mesh and side bands, means for shaping the bag provided with means for closing the mesh bag at the heart of a its lower base, means for filling each bag with the corresponding products, means for closing the upper mouth of the filled bags and means for transporting the filled and closed bags towards the exit of the machine.
These improvements are further characterized by the fact they have a set of at least three loose rollers which are horizontally disposed and vertically arranged or disposed, between which a tubular mesh is moved supplied with the interposition of a vertically disposed frame, in turn, with at least three other horizontally disposed loose rollers that rest, respectively, on the corresponding rollers of said set where the tubular mesh is inserted. The packing machine includes two opposite feeders of two thermoplastic material bands located underneath the loose rollers. The packing machine further includes two vertically disposed plates on the frame driven outwards by elastic means that attach them to the respective zone of the inside surface of the mesh, the zones having the respective bands superimposed there against, with welding means heat welding the two sides of each band applied to the mesh. Positioned underneath the welding means are two vertically disposed flat wheels that shape two folds towards the inside of the mesh parts free of the bands.
There are at least two opposed horizontally disposed rollers located below the flat wheels, which rollers turn in opposite directions, applied externally against the set formed by the tubular mesh and the two bands for their transport, with heatwelding means for closing the bottom of a bag. The mesh is then cut at its top portion to form the open end of the bag.
The improvements are further characterized by the fact that once each bag is filled with the desired product and closed at a certain distance underneath its mouth, the packing machine further includes feeder rollers of thermoplastic material bands, means for transversally cutting the bands in strips, two opposite turning lever means on the same plane that fold the strip in an inverted xe2x80x9cUxe2x80x9d shape with its free ends folded on each other, and other means that insert the folded strip into the upper part of the open mouth of the bag, combined with welds of each part together with the ends of the strip, obtaining the closed bag with the handle.
The improvements in the packing machines of products in mesh bags with handle, according to the invention, provide amongst others the following advantages as regards what is known:
a) The bands are not free as each one is fastened to the mesh of each bag by both sides.
b) There is no mobile tube to push and transport each bag with it being returned in ascent. Instead, there is a lower transport of the mesh with the two bands by pulling with a resulting increase in speed and better performance.
c) The bags obtained have an initially flat handle made of a strip with folds that unfolds when used.
d) The final handle, that is attached to the filled and closed bag, offers the bag carrier a flat part that opens on being unfolded and conveniently adapts itself to the hand and distributes the stress arising from the weight of the filled bag.
e) When the bags are filled with the desired products, their base does not rest on a stiff support, thus products being filled receive better treatment, especially delicate ones.
The improvement in packing machines for packing products in mesh bags with handles provide the advantages described above, apart from others that will be easily inferred from the performance example to be described in detail hereinafter. In order to facilitate understanding of the characteristics mentioned above and at the same time to make known various details, drawings are attached in which a practical performance case is represented as an example and not limitative of the scope of this invention.